From: "Lattannavar, Sameer" <sameer.lattannavar@intel.com>
To: Pekka Paalanen <ppaalanen@gmail.com>,
Hans de Goede <hdegoede@redhat.com>
Cc: Sebastian Wick <sebastian.wick@redhat.com>,
Martin Roukala <martin.roukala@mupuf.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
wayland <wayland-devel@lists.freedesktop.org>,
Christoph Grenz <christophg+lkml@grenz-bonn.de>,
Yusuf Khan <yusisamerican@gmail.com>
Subject: RE: [RFC] drm/kms: control display brightness through drm_connector properties
Date: Fri, 29 Apr 2022 09:49:54 +0000 [thread overview]
Message-ID: <MN0PR11MB60116B970F23F3DE101D66EA84FC9@MN0PR11MB6011.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20220429120651.5a39ec03@eldfell>
Yes we would need this.
-Sameer
-----Original Message-----
From: wayland-devel <wayland-devel-bounces@lists.freedesktop.org> On Behalf Of Pekka Paalanen
Sent: Friday, April 29, 2022 2:37 PM
To: Hans de Goede <hdegoede@redhat.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>; Sebastian Wick <sebastian.wick@redhat.com>; Martin Roukala <martin.roukala@mupuf.org>; Christoph Grenz <christophg+lkml@grenz-bonn.de>; wayland <wayland-devel@lists.freedesktop.org>; dri-devel@lists.freedesktop.org; Daniel Vetter <daniel@ffwll.ch>; Alex Deucher <alexdeucher@gmail.com>; Yusuf Khan <yusisamerican@gmail.com>
Subject: Re: [RFC] drm/kms: control display brightness through drm_connector properties
On Fri, 29 Apr 2022 08:59:24 +0000
Simon Ser <contact@emersion.fr> wrote:
> On Friday, April 29th, 2022 at 10:55, Hans de Goede <hdegoede@redhat.com> wrote:
>
> > I believe that we can fix the new interface, the plan is for there
> > to be some helper code to proxy the new connector properties to what
> > is still a good old backlight-device internally in the kernel,.
> >
> > This proxy-ing code could take a minimum value below which it should
> > not go when things are set through the properties and then if e.g.
> > the /sys/class/backlight interface offers range of 0-65535 and the
> > kms driver asks the proxying helper for a minimum of 500, show this
> > as 0-65035 on the property, simply adding 500 before sending the
> > value to the backlight-device on writes (and subtracting 500 on
> > reads, clamping to 0 as lowest value reported on reads).
> >
> > This way apps using the new API can never go below 500 (in this
> > example) and for old API users nothing changes.
> >
> > Given that Jani seems to be in favor of enforcing some minimal value
> > inside the i915 code going forward and also what Alex said that the
> > amdgpu code already enforces its own minimum if the video BIOS
> > tables don't provide one, it seems that there is consensus that we
> > want 0 to mean minimum brightness at which the screen is still
> > somewhat readable and that we want to enforce this at the kernel level.
> >
> > Which also means the weird hint property which I came up with won't
> > be necessary as we now have a clean definition of what brightness
> > 0 is supposed to mean (in the new API) and any cases where this is
> > not the case are kernel bugs and should be fixed in the kernel.
>
> Looks like a good approach to me from user-space PoV!
Yes!
Thanks,
pq
next prev parent reply other threads:[~2022-04-29 9:50 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 15:38 [RFC] drm/kms: control display brightness through drm_connector properties Hans de Goede
2022-04-07 16:51 ` Simon Ser
2022-04-07 17:43 ` Hans de Goede
2022-04-07 21:05 ` Alex Deucher
2022-04-08 8:07 ` Daniel Vetter
2022-04-08 9:58 ` Hans de Goede
2022-04-08 10:09 ` Hans de Goede
2022-04-08 10:16 ` Simon Ser
2022-04-08 10:26 ` Hans de Goede
2022-04-13 8:32 ` Daniel Vetter
2022-04-13 8:38 ` Simon Ser
2022-04-13 9:44 ` Hans de Goede
2022-04-08 10:23 ` Hans de Goede
2022-04-08 14:08 ` Alex Deucher
2022-04-08 14:55 ` Hans de Goede
2022-04-08 15:11 ` Alex Deucher
2022-04-11 10:18 ` Hans de Goede
2022-04-11 11:34 ` Pekka Paalanen
2022-04-11 11:50 ` Hans de Goede
2022-04-11 13:11 ` Mikhail Gusarov
2022-04-11 14:11 ` Alex Deucher
2022-04-14 10:24 ` Jani Nikula
2022-04-27 14:03 ` Daniel Vetter
2022-04-27 14:23 ` Jani Nikula
2022-04-27 14:26 ` Daniel Vetter
2022-04-29 8:55 ` Hans de Goede
2022-04-29 8:59 ` Simon Ser
2022-04-29 9:06 ` Pekka Paalanen
2022-04-29 9:49 ` Lattannavar, Sameer [this message]
2022-04-08 8:22 ` Simon Ser
2022-04-08 15:00 ` Hans de Goede
2022-04-11 10:35 ` Hans de Goede
2022-04-07 18:58 ` Carsten Haitzler
2022-04-11 10:27 ` Hans de Goede
2022-04-11 11:14 ` Carsten Haitzler
2022-04-14 13:10 ` Jani Nikula
2022-05-18 12:59 ` Hans de Goede
2022-05-18 14:23 ` Jani Nikula
2022-05-31 10:40 ` Hans de Goede
2022-05-18 14:40 ` Ville Syrjälä
2022-08-24 2:18 ` Yusuf Khan
2022-08-25 8:27 ` Hans de Goede
2022-08-25 21:40 ` Yusuf Khan
2022-08-28 8:08 ` Hans de Goede
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